Glossary · Phase 7 · Software engineering

Context manager

Also written: context managers

An object used with a with statement that sets something up at the start and always cleans up at the end.

Without with, you'd need a try/finally around every use to be sure the file gets closed. A context manager is any object that knows its own setup and cleanup. with calls them at the right moments.
From the lesson Context managers

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Step through to see the order: __enter__ runs first and its return value becomes status, the block runs, then __exit__ runs with None for the error.

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Context managers · Setup and cleanup that always run: with, contextlib, transactions and atomic writes. About 35 minutes.

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